001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
006 *
007 * Project Info: http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
022 * USA.
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
025 * in the United States and other countries.]
026 *
027 * ------------------
028 * LineUtilities.java
029 * ------------------
030 * (C) Copyright 2008, by Object Refinery Limited and Contributors.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes
036 * -------
037 * 05-Nov-2008 : Version 1 (DG);
038 *
039 */
040
041 package org.jfree.chart.util;
042
043 import java.awt.geom.Line2D;
044 import java.awt.geom.Rectangle2D;
045
046 /**
047 * Some utility methods for {@link Line2D} objects.
048 *
049 * @since 1.0.12
050 */
051 public class LineUtilities {
052
053 /**
054 * Clips the specified line to the given rectangle.
055 *
056 * @param line the line (<code>null</code> not permitted).
057 * @param rect the clipping rectangle (<code>null</code> not permitted).
058 *
059 * @return <code>true</code> if the clipped line is visible, and
060 * <code>false</code> otherwise.
061 */
062 public static boolean clipLine(Line2D line, Rectangle2D rect) {
063
064 double x1 = line.getX1();
065 double y1 = line.getY1();
066 double x2 = line.getX2();
067 double y2 = line.getY2();
068
069 double minX = rect.getMinX();
070 double maxX = rect.getMaxX();
071 double minY = rect.getMinY();
072 double maxY = rect.getMaxY();
073
074 int f1 = rect.outcode(x1, y1);
075 int f2 = rect.outcode(x2, y2);
076
077 while ((f1 | f2) != 0) {
078 if ((f1 & f2) != 0) {
079 return false;
080 }
081 double dx = (x2 - x1);
082 double dy = (y2 - y1);
083 // update (x1, y1), (x2, y2) and f1 and f2 using intersections
084 // then recheck
085 if (f1 != 0) {
086 // first point is outside, so we update it against one of the
087 // four sides then continue
088 if ((f1 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
089 && dx != 0.0) {
090 y1 = y1 + (minX - x1) * dy / dx;
091 x1 = minX;
092 }
093 else if ((f1 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
094 && dx != 0.0) {
095 y1 = y1 + (maxX - x1) * dy / dx;
096 x1 = maxX;
097 }
098 else if ((f1 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
099 && dy != 0.0) {
100 x1 = x1 + (maxY - y1) * dx / dy;
101 y1 = maxY;
102 }
103 else if ((f1 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
104 && dy != 0.0) {
105 x1 = x1 + (minY - y1) * dx / dy;
106 y1 = minY;
107 }
108 f1 = rect.outcode(x1, y1);
109 }
110 else if (f2 != 0) {
111 // second point is outside, so we update it against one of the
112 // four sides then continue
113 if ((f2 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
114 && dx != 0.0) {
115 y2 = y2 + (minX - x2) * dy / dx;
116 x2 = minX;
117 }
118 else if ((f2 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
119 && dx != 0.0) {
120 y2 = y2 + (maxX - x2) * dy / dx;
121 x2 = maxX;
122 }
123 else if ((f2 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
124 && dy != 0.0) {
125 x2 = x2 + (maxY - y2) * dx / dy;
126 y2 = maxY;
127 }
128 else if ((f2 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
129 && dy != 0.0) {
130 x2 = x2 + (minY - y2) * dx / dy;
131 y2 = minY;
132 }
133 f2 = rect.outcode(x2, y2);
134 }
135 }
136
137 line.setLine(x1, y1, x2, y2);
138 return true; // the line is visible - if it wasn't, we'd have
139 // returned false from within the while loop above
140
141 }
142 }